At least in Germany, queer tango has existed as long as modern tango. [
Queer Tango – Wikipedia]
But that subculture, with that name, has never really mattered to the mainstream; I think the term "queer" has a similar marketing appeal to the mainstream as "LGBT+". But this scene can, of course, integrate better into double-role events because heteronormative role models don't fit per se.
One indicator of the double-role evolution is Melina Sedo's "Pequena" encuentro. That was originally gender-balanced, then role-balanced, then with a 15% double-role quota, and now she flags a 25% double-role quota. (In fact this contradicts her announcement that she would no longer set an upper limit for double-role participants starting this year.)
You can see her effort to integrate a new customer group without alienating the existing customer group, especially heteronormative couples at such encuentros. The future will show whether the perception of what a "balanced" tango event looks like is actually slowly shifting.